High-Order Renormalized Perturbative Approach for Strongly-Correlated Fermions

In this talk I show how perturbation theory can be turned into a
viable computational approach for physical systems afflicted by the
fermionic sign problem. This is accomplished by designing new
numerical approaches to reach arbitrary-high orders for the bare [1]
and the renormalized [2] expansion. I discuss the results
obtained for the doped square-lattice Hubbard model in the pseudogap
regime, and in frustrated lattices. Finally, I present the first
unbiased diagrammatic computation in a broken-symmetry phase by
discussing the s-wave superfluid transition in the spin-polarized
cubic-lattice attractive Hubbard model.

[1] RR, Phys. Rev. Lett. 119, 045701 (2017)
[2] RR, Simkovic, Ferrero, EPL 132 11001 (2020)